On initiation of chemically assisted crack growth and crack propagation paths of branching cracks in polycarbonate

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On initiation of chemically assisted crack growth and crack propagation paths of branching cracks in polycarbonate

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dc.contributor.author Hejman, Ulf
dc.date.accessioned 2010-03-15T07:47:49Z
dc.date.available 2010-03-15T07:47:49Z
dc.date.issued 2010
dc.identifier.citation 77 en
dc.identifier.isbn 978-91-633-6462-4
dc.identifier.uri http://hdl.handle.net/2043/9955
dc.description.abstract Stress corrosion, SC, in some cases gives rise to stress corrosion cracking, SCC, which differs from purely stress intensity driven cracks in many aspects. They initiate and grow under the influence of an aggressive environment in a stressed substrate. They grow at low load and may branch. The phenomenon of SCC is very complex, both the initiation phase and crack extension itself of SCC is seemingly associated with arbitrariness due to the many unknown factors controlling the process. Such factors could be concentration of species in the environment, stress, stress concentration, electrical conditions, mass transport, and so on. In the present thesis, chemically assisted crack initiation and growth is studied with special focus on the initiation and branching of cracks. Polycarbonate plates are used as substrates subjected to an acetone environment. Experimental procedures for examining initiation and branching in polycarbonate are presented. An optical microscope is employed to study the substrate. The attack at initiation is quantified from pits found on the surface, and pits that act as origin for cracks is identified and the distribution is analysed. A growth criterion for surface cracks is formulated from the observations, and it is used to numerically simulate crack growth. The cracks are seen to coalesce, and this phenomenon is studied in detail. Branching sites of cracks growing in the bulk of polycarbonate are inspected at the sample surface. It is found that the total width of the crack branches are approximately the same as the width of the original crack. Also, angles of the branches are studied. Further, for comparison the crack growth in the bulk is simulated using a moving boundary problem based algorithm and similar behaviour of crack branching is found. en
dc.language.iso eng en
dc.publisher Ulf Hejman/Media-Tryck AB en
dc.relation.haspart U. Hejman, C. Bjerkén. "Environmentally assisted initiation and growth of multiple surface cracks". Submitted for publication.
dc.relation.haspart U. Hejman, C. Bjerkén. "Branching cracks in a layered material - Dissolution driven crack growth in polycarbonate". Submitted for publication.
dc.subject stress corrosion en
dc.subject crack initiation en
dc.subject multiple cracking en
dc.subject polycarbonate en
dc.subject three point bending en
dc.subject stress corrosion cracking en
dc.subject polycarbonate en
dc.subject dissolution en
dc.subject branching en
dc.subject experiment en
dc.subject finite element modelling en
dc.subject.classification Sciences en
dc.title On initiation of chemically assisted crack growth and crack propagation paths of branching cracks in polycarbonate en
dc.type Licentiate Thesis en
dc.identifier.paperprint 0 en
dc.contributor.department Malmö University. School of Technology en
dc.subject.srsc Research Subject Categories::MATHEMATICS::Applied mathematics::Numerical analysis en
dc.subject.srsc Research Subject Categories::TECHNOLOGY::Engineering mechanics::Solid mechanics en
dc.subject.srsc Research Subject Categories::TECHNOLOGY::Materials science::Surface engineering en
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